The present invention relates to thermally developable light-sensitive material comprising a specific dye, a silver halide light-sensitive material comprising said specific dye, an image forming method using the same, a filter comprising said specific dye, and a support comprising said specific dye usable for a silver halide photosensitive material.
In exposing a light-sensitive material to light, incident light is reflected or refracted by a silver halide, other additives, or at a layer interface, and as a result, the image dims and resolution degrades. In order to prevent such resolution degradation, an anti-halation (AH) dye or an anti-irradiation (AI) dye have been widely employed.
Conventionally, necessary characteristics of these AH and AI dyes are the following: they absorb a desired wavelength of light; they do not give an adverse effect to a silver halide emulsion; and they completely decolor or leach out of a photosensitive material so as not to leave any residual color stain in said photosensitive material.
In recent years, the trend toward more and more rapid developing processes and a dry developing process have been marked, and color stain derived from these dyes after processing a light-sensitive material, namely, residual color stain, has received much study. Therefore, reducing said residual color stain has been strongly demanded. Specifically, in the case of a dry process, using no water, in which dyes can not leach out of said photosensitive material, said residual color stain tends to become critical, therefore, reducing said residual color stain has become a point of focus.
Representative AI and AH dyes which can absorb infrared rays are organic dyes, and many such organic dyes have been suggested. Among them, specifically used have been cyanine and oxonol dyes. However, absorption in the visible region of these dyes is relatively large, and these dyes are also marginal effectiveness in preventing said residual color stain, since decomposed compounds derived from these dyes absorb yellow light. Further, these compounds are relatively unstable and decomposable, and still further, synthesizing these compounds is relatively expensive.
The solubility of squarylium dye and croconium dye in an organic solvent is, in general, relatively low, therefore, additon of these dyes into a silver halide photographic light-sensitive material is very challenging. Further, since spectral absorption characteristics of these dyes, in the form of a dispersion, tend to vary, reducing the sectral absorption characteristics has been demanded.
A thermally developable photographic light-sensitive material comprising a squarylium dye having a naphthalene ring is disclosed in Japanese Patent Publication to Public Inspection under PCT Application No. 9-509503, as well as in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP-A) Nos. 8-262986, 10-236695, 10-104779, 10-158253 and 10-204310, however, these dyes are tinged with yellow, and therefore, their residual color stain is unacceptable. Furthermore, heat stability of these dyes is also unacceptable, so that storage stability of these dyes, used in a light-sensitive material is also critical. An image forming method described in JP-A No. 10-24654 is one in which an image is formed directly merely by exposing a light-sensitive material to infrared rays (thermally dye forming), however, said method does not refer to an image forming method in which a light-sensitive, material is exposed to light to form a latent image, and said light-sensitive material, in which said latent image is formed, must be subjected to thermal development so as to form an visible image. The present inventive employees have made a great effort to solve the above-mentioned problems and finally found a way to obtain xe2x80x9ca blue-black tonexe2x80x9d of a formed silver image which is desired to be applicable to a direct appreciation or the medical diagnosis. Solubility of S-1 and S-4 described in JP-A No. 10-24654 is relatively low in organic solvents, since these dyes have four hydroxy groups in their molecules, and therefore, sufficient antihalation and antiirradiation effect can not be obtained. Dyes described in JP-A Nos. 10-36695 and 10-158253 are difficult to commercially produce. Solubility of dyes described in JP-A 10-104779 in an organic solvent is relatively low and the cost for producing them is relatively expensive.
Squarylium dye having a thiopyrylium nucleous (being termed thiopyryliumsquarylium dye in the present invention, while squarylium dye having pyrylium nucleous is termed pyryliumsquarylium dye) is described in U.S. Pat. Nos. 4,508,811, and 5,667,943. However, these patents do not propose nor suggest that said thiopyryliumsquarylium dye can be applied to a silver halide photosensitive material.
An object of the present invention is to provide a thermally developable photographic light-sensitive material and a silver halide photographic light-sensitive material, capable of producing various preferable photographic characteristics of a formed image, such as a silver image of excellent resolution, less residual color stain, preferable blue-black silver image tone, excellent image stability when stored over a long period of time, employing a dye which is excellent in solubility in an organic solvent, and finally, one which exhibits desirable dispersibility in the form of a solid dispersion or an oil dispersion. Another object of the present invention is to provide a thermally developable photographic light-sensitive material as well as a silver halide photographic light-sensitive material, which are suitably applicable to a dry process by employing said dye, cited above, and an image forming method by which said thermally developable photographic light-sensitive material and said silver halide photographic light-sensitive material are processed, and further, an optical filter having preferable characteristics provided by employing said dye, and still further, a support for a silver halide light-sensitive material provided, employing said dye.
The above-mentioned objects of the present invention are attained by the following constitution.
(1) A silver halide photographic light-sensitive material comprising a dye represented by the following formula (1) or formula (2): 
wherein A1 and B1 each represent substituents other than a naphthalene group; and A2 and B2 represent substituents.
(2) The silver halide photographic light-sensitive material of item 1, wherein said dye represented by said formula (1) or said formula (2) is a dye represented by the following formula (3) or formula (4): 
wherein R1, R2, R3 and R4 each represent a hydrogen atom or an alkyl group; each of A3, B3, A4 and B4 is symmetrical so that a structure obtained by rotating each of A3, B3, A4 and B4 by 180 degrees around the bond connecting each of A3, B3, A4 and B4 with a carbon atom attached to each of A3, B3, A4 and B4 leads to the same structure as each original structure of A3, B3, A4 and B4; the sum total of hydroxy group contained in A3 and B3 is 0 or 1; and the sum total of hydroxy group contained in A4 and B4 is 0 or 1.
(3) The silver halide photographic light-sensitive material of item 2, wherein said dye represented by said formula (3) or said formula (4) is a dye represented by the following formula (5) or formula (6): 
wherein R1, R2, R3 and R4 each represent a hydrogen atom or an alkyl group; ZA3, ZB3, ZA4 and ZB4 each represent a group of atoms necessary for forming a 6-membered heterocyclic ring with a carbon atom.
(4) The silver halide photographic light-sensitive material of item 1, wherein said dye is represented by said formula (1).
(5) The silver halide photographic light-sensitive material of item 1, wherein said dye is represented by said formula (2).
(6) The silver halide photographic light-sensitive material of item 5, wherein said dye is represented by the following formula (11). 
wherein R1, R2, R3 and R4 each represent an alkyl group on which an acidic substituent does not substitute; R5 and R6 each represent a monovalent substituent; and 1 and m each are an integer of 0 to 4.
(7) The silver halide photographic light-sensitive material of item 6, wherein at least one of R1, R2, R3 and R4 of said formula (11) is an alkyl group substituted with an alkoxy group, or an alkyl group having at least five carbon atoms.
(8) The silver halide photographic light-sensitive material of item 1, wherein said silver halide photographic light-sensitive material is exposed to light to form a latent image, and said silver halide photographic light-sensitive material, in which said latent image is formed, is followed by being subjected to thermal development so as to substantially form an image.
(9) The silver halide photographic light-sensitive material of item 1, wherein said silver halide photographic light-sensitive material comprises a component layer containing said dye represented by said formula (1) or said formula (2), and a water-soluble binder.
(10) The silver halide photographic light-sensitive material of claim 9, wherein said silver halide photographic light-sensitive material comprises a component layer containing said dye represented by said formula (1), and said water-soluble binder.
(11) The silver halide photographic light-sensitive material of item 10, wherein said component layer, containing said dye represented by said formula (1) and said water-soluble binder, is spectrally sensitized to the wavelength region of 600 nm to 700 nm.
(12) The silver halide photographic light-sensitive material of item 1, wherein said silver halide photographic light-sensitive material comprises a hydrazine compound.
(13) The silver halide photographic light-sensitive material of item 1, wherein said silver halide photographic light-sensitive material comprises said dye, represented by said formula (1) or said formula (2), in the form of a solid dispersion or an oil dispersion.
(14) The silver halide photographic light-sensitive material of item 9, wherein said component layer, containing said dye represented by said formula (1) or said formula (2) and said water-soluble binder, is spectrally sensitized to the wavelength region of 600 nm to 900 nm.
(15) A silver halide light-sensitive material comprising at least a dye selected from a group consisting of thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye.
(16) The silver halide light-sensitive material of item 15, wherein said dye, selected from said group consisting of thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye, has a molecular nucleus represented by the following formula (7): 
wherein X1 and X2 represent an oxygen atom, a sulfur atom, a selenium atom or tellurium atom; R5 and R6 represent a hydrogen atom and an alkyl group.
(17) The silver halide light-sensitive material of item 16, wherein said formula (7) is represented by the following formula (8): 
wherein X1 and X2 represent a oxygen atom, a sulfur atom, a selenium atom or tellurium atom; R5 and R6 represent a hydrogen atom and an alkyl group; R7 and R8 represent a monovalent substituent, and plural R7 and plural R8 may form a ring structure with each other; m and n represent an integer of 0 to 4.
(18) The silver halide light-sensitive material of item 15, wherein said silver halide light-sensitive material comprises a component layer containing at least a dye selected from said group consisting of thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye, and further containing a water-soluble binder.
(19) The silver halide light-sensitive material of item 15, wherein said silver halide light-sensitive material comprises at least a dye selected from said group consisting of thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye, in the form of a solid dispersion or an oil dispersion.
(20) The silver halide light-sensitive material of item 15, wherein said silver halide light-sensitive material comprises a hydrazine compound.
The present invention will now be detailed below.
First, a dye represented by the formula (1) will be explained.
In a dye represented by the formula (1), A1 and B1 each represent substituents other than a naphthalene group. Examples of A1 and B1 include an alkyl group, an alkenyl group, a cycloalkyl group, a phenyl group or a heterocyclic group, while preferable examples of A1 and B1 include an alkenyl group, a phenyl group and a heterocyclic group, with the most preferable example being an alkenyl group.
A dye represented by the formula (2) will be explained below.
In a dye represented by the formula (2), A2 and B2 each represent substituents. Examples of A2 and B2 include an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group and a heterocyclic group, and preferable examples of A2 and B2 include an alkenyl group, an aryl group and a heterocyclic group. Most preferable example is an alkenyl group.
Dyes represented by the formulas (3) and (4) will be explained below.
In dyes represented by said formulas (3) and (4), each of A3, B3, A4 and B4 is symmetrical form so that a structure obtained by rotating each of A3, B3, A4 and B4 180 degrees around the bond connecting each of A3, B3, A4 and B4 with a carbon atom attached to each of A3, B3, A4 and B4 leads to the same structure as each original structure of A3, B3, A4 and B4, with the preferable structure for each of A3, B3, A4 and B4 being a 6-membered monoheterocyclic ring. The sum total of hydroxy group contained in A3 and B3 is 0 or 1; the sum total of hydroxy group contained in A4 and B4 is also 0 or 1, while the sum total of hydroxy group contained in A3 and B3, or A4 and B4 is preferably 0.
Dyes represented by the formula (5) and formula (6) will be explained.
In the formula (5) and formula (6), R1, R2, R3 and R4 each represent a hydrogen atom or an alkyl group; ZA3, ZB3, ZA4 and ZB4 each represent a group of atoms necessary for forming a 6-membered heterocyclic ring with a carbon atom, and said formed 6-membered heterocyclic ring is preferably a 6-membered monoheterocyclic ring containing one hetero-atom in said 6-membered monoheterocyclic ring. Preferable examples of hetero-atoms are a nitrogen atom or a sulfur atom.
In the present invention, thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye have a thiopyrylium nucleus, a pyrylium nucleus and a squarylium dye, a croconium dye, a selenapyrylium dye and a telluropyrylium dye.
A compound having a squarylium nucleus is a compound having 1-cyclobutene-2-hydroxy-4-one in its molecular structure, and a compound having a croconium nucleus is a compound having 1-cyclopentene-2-hydroxy-4,5-dione. Herein, a hydroxy group may be dissociated.
Formula (7) of the present invention represents only a mother nucleus which may be substituted with an appropriate substituent.
In the formula (8) of the present invention, R7 and R8 each represent a monovalent substituent. Examples of said monovalent substituent are not specifically limited, but preferable are an alkyl group (for example, a methyl group, an ethyl group, an iso-propyl group, a tert-butyl group, a methoxyethyl group, a methoxyethoxyethyl group, a 2-ethylhexyl group, a 2-hexyldecyl group, a benzyl group), or an aryl group (for example, a phenyl group, a 4-chlorophenyl group, a 2,6-dimethylphenyl group), while more preferable is an alkyl group, and most preferable is a tert-butyl group. R7 and R8 may also form a ring with each other. m and n each represent an integer of 0 to 4, and each of m and n is preferably not more than 2.
Exemplified dyes used in the present invention are illustrated below, but the present invention is not limited thereto. 
Thiopyryliumsquarylium dye, thiopyryliumcroconium dye, pyryliumsquarylium dye, pyryliumcroconium dye, selenapyryliumsquarylium dye, selenapyryliumcroconium dye, telluropyryliumsquarylium dye, and telluropyryliumcroconium dye. 
Formula (11) of the present invention will be explained below.
In the formula (11), R1, R2, R3 and R4 each represent an alkyl group which does not contain an acidic substituent in said alkyl group; R5 and R6 each represent a monovalent substituent.
Examples of R1, R2, R3 and R4 include a methyl group, an ethyl group, an iso-propyl group, a tert-butyl group, a methoxyethyl group, a methoxyethoxyethyl group, a 2-ethylhexyl group, a 2-hexyldecyl group or a benzyl group. In the present invention, an acidic substituent represents a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, xe2x80x94SO2NHSO2R or xe2x80x94CONHSO2R (R represents a lower alkyl group having 1 to 5 carbon atoms or a phenyl group). The sulfonic acid group includes a sulfo group or its salt, with the carboxylic acid group including a carboxyl group or its salt, while the phosphoric acid group includes a phosphono group or its salt.
When R1, R2, R3 and R4 represent an alkyl group substituted with an alkoxy group or an alkyl group having 5 or more carbon atoms, it is preferred that solubility of the dye represented by the formula (11) in an organic solvent is improved. Examples of a monovalent substituent represented by R5 and R6 are not limited, but preferable examples of said monovalent substituent include an alkyl group (e.g. an alkyl group represented by R1), an aryl group (e.g. a phenyl group, a 4-chlorophenyl group, a 2,6-dimethyphenyl group), a hydroxyl group, an amino group, or an acyl group (e.g. an acetyl group), while the preferable examples are an alkyl group, an aryl group or a hydroxyl group. From the viewpoint of ease of synthesis and preferable spectral absorption, a hydroxyl group is most preferable.
R1, R2, R3, R4, R5 and R6 may form a ring with each other, for example, R1, R2 and R5 may form a durolidyl ring with each other. 1 and m each represent an integer of 0 to 4, however, from the viewpoint of ease in synthesis, 1 and m are preferably 0 or 1, and, from the viewpoint of desirable spectral absorption characteristic, 1 and m are preferably to be 1.
Exemplified dyes represented by the formula (11) are illustrated below, but the present invention is not limited thereto. 
Exemplified synthesizing methods will be illustrated below, but the present invention is not limited thereto. 
To 20 ml of 1-propanol were added 2.39 g of an intermediate compound 1 and 0.75 g of croconic acid. The thus obtained mixture was refluxed by heating for 1 hour, after which reaction products were extracted with ethyl acetate. Following that, the organic solvent phase containing the target compound was washed with water, after which the organic solvent was removed to leave a residue, which was recrystallized from methanol to produce dark greenish crystals at a 72% yield. The chemical structure of the thus obtained exemplified compound 1 was confirmed by MASS spectrum and NMR spectrum. xcexmax of the exemplified compound was 813 nm in ethyl acetate.
Other exemplified compounds can be synthesized according to the method described above.
xe2x80x9cA silver halide photographic light-sensitive material is exposed to light to form a latent image, and said silver halide photographic light-sensitive material, in which said latent image is formed, is followed by being subjected to thermal development so as to substantially form an imagexe2x80x9d, will be explained in detail below. The exposing method is not limited and every kind of exposing method is acceptable. However, as a light source, a laser light source is preferable. As a laser light source useful in the present invention, preferably cited are a gas laser, a YAG laser, a dye laser and semiconductor laser. Furthermore, combinations of a semiconductor laser and a secondary high frequency wavelength generating element are also viable. The energy of the exposing light is preferably between 1 mmJ/mm2 and 40 mmJ/mm2 per mm sec. A latent image may not substantially be recognized with the naked eye, however, said latent image can be recognized with the naked eye follwing the developing process, and the term, xe2x80x9csaid latent imagexe2x80x9d is well known in this art. The heat in the present inventive thermally developing process is preferably between 80xc2x0 C. and 200xc2x0 C., is more preferably between 100xc2x0 C. and 150xc2x0 C. When the heat is less than 80xc2x0 C., a sufficient image density is not obtained in the desired short time. On the other hand, when the heat is more than 200xc2x0 C., the binder is melted to result in adhesion to the rollers, as well as other adverse effects such as an unpreferable transferability and unacceptable developing machine problems. Developing time is preferably between 1 to 180 sec., and is more preferably 10 to 90 sec. Any known developing method may be employed, however, a light-sensitive material is preferably heated on a roller or a heat block heated to the desired temperature. A thermally developable light-sensitive material of the present invention is processed by a thermally developing process to obtain a photographic image, and said thermally developable light-sensitive material comprises a light-sensitive silver halide and, if necessary, for example, an organic silver salt as a reducible silver source, as well as an image toner to control a silver image tone in the form of a dispersion state or a solution state in a binder-matrix. The thermally developable light-sensitive material of the present invention is stable at normal temperatures and is developed, after exposure, when heated to higher temperatures (for example, not lower than 80xc2x0 C.). Image formation is conducted by only the heating without any further supply of a processing solution such as water, etc. from outside, therefore, since this processing generates no processing solution waste, it is preferable from the viewpoint of environmental concerns.
A silver halide photographic light-sensitive material, to which the present invention applies, is not limited, and examples of said silver halide photographic light-sensitive material, to which the present invention is applied, include a known color negative film, a color reversal film, a color paper, a graphic art film, and a medical X-ray film. Of these, preferred ones are said graphic art film and medical X-ray film, and most preferable are the graphic art film and X-ray film by which an image is formed via the above-mentioned thermal development.
The average particle size of the dye in the form of a solid dispersion is expressed as the diameter of a sphere which has the same volume as the dye in the form of said solid dispersion, with the average particle diameter being preferably between 0.05 and 3.0 xcexcm. The diameter of 70 wt % or more of the dye particles is preferably between 0.1 and 1.5 xcexcm, and is more preferably between 0.1 to 1.0 xcexcm. The diameter of the dye particle can be measured with a particle size measuring apparatus utilizing light scattering by coherent light such as light or laser light. The shape of the dye particle is almost spherical. The dye of the present invention in the form of said solid dispersion is preferably provided in the form of a fine solid particle dispersion prepared in the presence of a dispersant, in order to obtain fine particles which do not coagulate. As to a method by which the dye of the present invention is dispersed in the form of said fine particles, the dye is mechanically dispersed in the presence of an auxiliary dispersing agent by means of any of several known method to produce a fine particle dispersion (for example, a ball mill, a vibration ball mill, a planet ball mill, a sand mill, a colloid mill, a jet mill, and a roller mill). Furthermore, the dye is dissolved in a water-insoluble solvent, the boiling point of which is lower than that of water, and the thus obtained solvent containing the dye is subjected to ultrasonic dispersion to obtain fine oil droplets, after which the solvent is distilled by heating to obtain a fine solid dispersion.
When the dye is prepared in the form of a fine solid dispersion by the use of a dispersant, may be any of dispersant used those as described below; synthesized anionic polymers such as polyacrylic acid, copolymer derived from acrylic acid, copolymer derived from maleic acid, copolymer derived from maleic acid monoester, and copolymer derived from acryloylmethylpropanesulfonic acid; half-synthesized polymers such as carboxymethyl starch and carboxymethyl cellulose; anionic polymers such as alginic acid and pectic acid; anionic surfactants described in JP-A No. 52-92716, and WO No. 88/04794; compounds described in Japanese Patent Application No. 7-350753; a known anionic, nonionic, and cationic surfactant; in addition, known polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose; high molecular compounds naturally existing, such as gelatin, etc. Any of the above-mentioned compounds may be selected for use, as appropriate
The dispersant is mixed with the dye provided in the form of a powder or in the form of a wet cake (thick paste) before dispersion, and the thus obtained mixture is usually fed into a homogenizer in a slurry state. The dispersant may be previously mixed with the dye, and the thus obtained mixture may be subjected to heat treatment or solvent treatment to be fed into the homogenizer. The pH of said mixture may be controlled by the use of a pH controlling agent, before, after, or during the dispersion.
Other than mechanically dispersing, the dye is primarily dispersed in a solvent by controlling the pH, after which fine particle dispersion of the dye can be obtained by varying the pH in the presence of an auxiliary dispersing agent. At that time, as a solvent used for primary dispersing, an organic solvent may be used, and said organic solvent is usually removed after obtaining said fine particle dispersion.
The thus prepared fine solid particle dispersion can be stored, while stirring said dispersion for the purpose of preventing precipitation of the fine particles, or while keeping said dispersion in the highly viscous state formed with a hydrophilic colloid (for example, in the state of a jell formed by the use of gelatin). An antiseptic can be added to said dispersion to prevent the propagation of germs.
The dye of the present invention is dissolved in a water-insoluble high boiling solvent (for example, tricresyl phosphate, di-butyl phthalate, di-nonylphenol, etc.) and the thus obtained solution is subjected to ultrasonic dispersion or the like to obtain said fine oil dispersion. The boiling point of said water-insoluble high boiling solvent is preferably 100xc2x0 C., and is more preferably between 140 and 300xc2x0 C. Examples of the medium used for dispersing said fine oil dispersion include those described below; synthesized anionic polymers such as polyacrylic acid, copolymer derived from acrylic acid, copolymer derived from maleic acid, copolymer derived from maleic acid monoester, and copolymer derived from acryloylmethylpropanesulfonic acid; half-synthesized polymers such as carboxymethyl starch and carboxymethyl cellulose; anionic polymers such as alginic acid and pectic acid; anionic surfactants described in JP-A No. 52-92716, and WO No. 88/04794; compounds described in Japanese Patent Application No. 7-350753; any commonly known anionic, nonionic, and cationic surfactant; in addition, known polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose; any naturally existing high molecular compounds, such as gelatin, etc. Any of the above-mentioned compounds may be selected for use as appropriate.
Examples of a water-soluble binder of the present invention include water-soluble polymers such as gelatin and/or gelatin derivatives (for example, phthalated gelatin, etc.), polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose; as well as various kinds of emulsions such as gum arabi, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-polyvinyl acetate copolymer.
The amount of binder used is preferably between 0.5 and 5 g/m2 in terms of solid composition. The preferable water-soluble binder used in the present invention is a styrene-butadiene copolymer latex. The weight ratio of the monomer unit of styrene to the monomer unit of butadiene contained in said styrene-butadiene copolymer latex is preferably between 50:50 to 95:5.
Examples of preferable styrene-butadiene copolymer latex include LACSTAR 3307B, 7132C, DS206, Nipol Lx 416, Lx 433, which are all commercially available.
A silver halide photographic light-sensitive material, which is spectrally sensitized to the wavelength region of 600 to 700 nm, is a silver halide photographic light-sensitive material, which can substantially form an image through an operation in which said silver halide photographic light-sensitive material is thermally developed after exposing it to a light source at wavelengths between 600 and 700 nm. A laser light source is preferable as said light source, Examples of preferable laser light sources used in the present invention include a gas laser, a YAG laser, a dye laser, and a semiconductor laser, and combined usage of a semiconductor laser and a secondary high frequency wavelength generating element is acceptable. The energy of said exposing light is preferably between 1 mmJ/mm2 and 40 mmJ/mm2 oer mm sec.
As hydrazine derivatives employed in the present invention, preferred are those having the following general formula (H). 
wherein A0 represents an aliphatic group, an aromatic group, a C0xe2x80x94D0 group, or a heterocyclic group, each of which may have a substituent; B0 represents a blocking group; both A1 and A2 represent hydrogen atoms, or one of which represents a hydrogen atom and the other represents an acyl group, a sulfonyl group or an oxalyl group. C0 represents a xe2x80x94COxe2x80x94 group, a xe2x80x94COCOxe2x80x94 group, a xe2x80x94CSxe2x80x94 group, a xe2x80x94C(xe2x95x90NG1D1)xe2x80x94 group, a xe2x80x94SOxe2x80x94 group, a xe2x80x94SO2xe2x80x94 group or a xe2x80x94P(O)(G1D1)xe2x80x94 group; G1 represents a simple linking groups such as a xe2x80x94Oxe2x80x94 group, xe2x80x94Sxe2x80x94 group, or xe2x80x94N(D1)xe2x80x94 group; D1 represents an aliphatic group, an aromatic group, a heterocyclic group, or a hydrogen atom; and D0 represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group.
In general formula (H), aliphatic groups represented by A0 preferably have from 1 to 30 carbon atoms, and straight, branched or cyclic alkyl groups having from 1 to 20 carbon atoms are particularly preferred and, for example, cited are a methyl group, an ethyl group, a t-butyl group, an octyl group, a cyclohexyl group, and a benzyl group. These may be substituted with a suitable substituent (for example, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, arylthio group, a sulfoxy group, a sulfonamide group, a sulfamoyl group, an acylamino group, a ureido group, etc.).
In the general formula (H), aromatic groups represented by A0 are preferably monoring or condensed ring aryl groups, and cited, for example, are a benzene ring and a naphthalene ring. Heterocyclic groups represented by A0 are preferably monoring or condensed ring groups composed of a heterocycle containing at least one hetero atom selected from nitrogen, sulfur, and oxygen atoms, which are, for example, a pyrrolidone ring, an imidazole ring, a tetrahydrofuran ring, a morpholine ring, a pyridine ring, a pyrimidine ring, a quinoline ring, a thiazole ring, a benzothiazole ring, a thiophene ring, or a furan ring; as A0, those particularly preferred are an aryl group, and aromatic groups and heterocyclic groups of A0 may have a substituent and particularly preferred groups include a substituent having an acidic group with a pKa of 7 to 11, and specifically cited are a sulfonamide group, a hydroxyl group, a mercapto group, etc.
In the general formula (H), the xe2x80x94G0xe2x80x94D0xe2x80x94 group represented by A0 will now be described.
G0 represents a xe2x80x94COxe2x80x94 group, a xe2x80x94COCOxe2x80x94 group, a xe2x80x94CSxe2x80x94 group, a xe2x80x94C(xe2x95x90NG1D1)xe2x80x94 group, a xe2x80x94SOxe2x80x94 group, a xe2x80x94SO2xe2x80x94 group, or a xe2x80x94P(O)(G1D1)xe2x80x94 group, and as preferred G0, listed are a xe2x80x94COxe2x80x94 group and a xe2x80x94COCOxe2x80x94 group, and as particularly preferred, a xe2x80x94COCOxe2x80x94 group is listed. G1 represents a simple linking group such as a xe2x80x94Oxe2x80x94 group, a xe2x80x94Sxe2x80x94 group or a xe2x80x94N(D1)xe2x80x94 group, and D1 represents an aliphatic group, an aromatic group, a heterocyclic group, or a hydrogen atom, and when a plurality of D1s are present in a molecule, these may be the same or different.
D0 represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, and as preferred D0, listed are a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aryl group, etc.
Furthermore, in the general formula (H), A0 preferably contains at least one of a nondiffusion group or a silver halide adsorption group. As the nondiffusion group, a ballast group is preferred which is commonly used as immobilizing photographic additives such as couplers, and the ballast groups include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a phenyl group, a phenoxy group, an alkylphenoxy group, etc. which have at least 8 carbon atoms and are photographically inactive.
In the general formula (H), silver halide adsorption accelerators include thiourea, a thiourethane group, a mercapto group, a thioether group, a thione group, a heterocyclic groups, a thioamido heterocyclic group, a mercapto heterocyclic group, or adsorption groups described in Japanese Patent Publication Open to Public Inspection No. 64-90439.
In the general formula (H), B0 represents a blocking group; preferably represents xe2x80x94G0xe2x80x94D0 which is the same as the xe2x80x94G0xe2x80x94D0 group in A0, and A0 and B0 may be different.
Both A1 and A2 represent a hydrogen atom and when one of them represents a hydrogen atom, the other represents an acyl group (for example, an acetyl group, a trifluoroacetyl group, a benzoyl group, etc.), a sulfonyl group (for example, a methanesulfonyl group, a toluenesulfonyl group, etc.), or an oxalyl group (for example, an ethoxalyl group, etc.).
Specific examples represented by the general formula (H) are described below. However, the present invention is not limited to these examples. 
As hydrazine compounds employed in the present invention, other than the compounds described above, those described below may also be employed.
In addition to the compounds described in Research Disclosure, Item 23516 (November 1983 Issue, page 346) and publications cited therein, listed can be those described in U.S. Pat. Nos. 4,080,207, 4,269,929, 4,276,364, 4,278,748, 4,385,108, 4,459,347, 4,478,928, 4,560,638, 4,686,167, 4,912,016, 4,988,604, 4,994,365, 5,041,355, and 5,104,769; U.K. Patent No. 2,011,391B; European Patent Nos. 217310, 301,799, and 356,898; and Japanese Patent Publication Open to Public Inspection Nos. 60-179734, 61-170733, 61-270744, 62-178246, 62-270948, 63-29751, 63-32538, 63-104047, 63-121838, 63-129337, 63-223744, 63-234244, 63-234245, 63-234246, 63-294552, 63-306438, 64-10233, 1-90439, 1-100530, 1-105941, 1-105943, 1-276128, 1-280747, 1-283548, 1-283549, 1-285940, 2-2541, 2-77057, 2-139538, 2-196234, 2-196235, 2-198440, 2-198441, 2-198442, 2-220042, 2-221953, 2-221954, 2-285342, 2-285343, 2-289843, 2-302750, 2-304550, 3-37642, 3-54549, 3-125134, 3-184039, 3-240036, 3-240037, 3-259240, 3-280038, 3-282536, 4-51143, 4-56842, 4-84134, 2-230233, 4-96053, 4-216544, 5-45761, 5-45762, 5-45763, 5-45764, 5-45765, 6-289524, and 9-160164, etc.
Furthermore, other than those, employed can be compounds described in (Ka 1) of Japanese Patent Publication No. 6-77138, specifically, compounds described on pages 3 and 4 of the Publication; compounds represented by general formula (I) in Japanese Patent Publication No. 6-93082, specifically, compounds 1 through 38 described on pages 8 to 18 of the Publication; compounds represented by general formula (4), general formula (5), and general formula (6) in Japanese Patent Publication Open to Public Inspection No. 6-230497, specifically, compounds 4-1 through 4-10 on pages 25 and 26, compounds 5-1 through 5-42 on pages 28 to 36, and compounds 6-1 through 6-7 on pages 39 and 40 of the Publication; compounds represented by general formula (I) and general formula (2) in Japanese Patent Publication Open to Public Inspection No. 6-289520, specifically, compounds 1-1) through 1-17) and 2-1) on pages 5 to 7 of the Publication; compounds described in (Ka 2) and (Ka 3) of Japanese Patent Publication Open, to Public Inspection No. 6-313936, specifically, compounds described on pages 6 to 19 of the Publication; compounds described in (Ka 1) of Japanese Patent Publication Open to Public Inspection No. 6-313951, specifically, compounds described on pages 3 to 5 of the Publication; compounds represented by general formula (I) in Japanese Patent Publication Open to Public Inspection No. 7-5610, specifically, compounds I-1 through I-38 described on pages 5 to 10 of the Publication; compounds represented by general formula (II) in Japanese Patent Publication Open to Public Inspection No. 7-77783, specifically, compounds II-1 through II-102 described on pages 10 to 27 of the Publication; and compounds represented by general formula (H) and general formula (Ha) in Japanese Patent Publication Open to Public Inspection No. 7-104426, specifically, compounds H-1 through H-44 described on pages 8 to 15 of the Publication.
A hydrazine derivative addition layer is a photosensitive layer and/or a constitution layer adjacent to the photosensitive layer. The added amount is preferably in the range of 10xe2x88x926 to 10xe2x88x921 mole per mole of silver halide and is most preferably in the range of 10xe2x88x925 to 10xe2x88x922 mole, though the optimum amount is not defined, depending on the silver halide grain size, halide composition, chemical sensitization degree, reducing agent type, retarder type, etc.
A silver halide photographic light-sensitive material, which is spectrally sensitized to the wavelength region of 600 to 900 nm, is a silver halide photographic light-sensitive material, which can substantially form an image through an operation in which said silver halide photographic light-sensitive material is thermally developed after exposing it to a light source in the wavelength region between 600 and 900 nm. As said light source, a laser light source is preferable. Examples of the preferable laser light used in the present invention include a gas laser, a YAG laser, a dye laser, and a semiconductor laser, and combined usage of a semiconductor laser and a secondary high frequency wavelength generating element is available. The energy of the exposing light is preferably between 1 mmJ/mm2 and 40 mmJ/mm2 per mm sec.
The additional amount of the dye of the present invention incorporated into the thermally developable photosensitive material, the silver halide photographic light-sensitive material, the optical filter, and the support usable for a silver halide photographic light-sensitive material is not limited, but it is preferable that said additional amount is controlled so that a transmission density at the spectral maximum of the dye is between 0.01 to 3.0, and is more preferably between 0.1 to 1.5.
The dye may be incorporated into any layer of the thermally developable photosensitive material and the silver halide photographic light-sensitive material, but the dye is preferably incorporated in the light-sensitive layer or the backing layer, and is specifically preferably incorporated into said light-sensitive layer. It is preferable that the dye is dissolved in an organic solvent (e.g. methylethyl ketone, ethyl acetate, and toluene) and directly added to the photographic light-sensitive material. In addition, dye in the form of a solid dispersion and dye in the form of an oil dispersion are preferably employed.
The light-sensitive material can comprise the dye of the present invention on both sides of a support, however, preferably the dye is comprised in the layer provided opposite to the emulsion layer. Furthermore, in the present invention, when the dye is incorporated into the support itself, it results in a marked improvement of resolution.
The processing method of a silver halide photographic light-sensitive material of the present invention is not specifically limited, and said silver halide photographic light-sensitive material may be processed in a processing solution such as C-41, produced by Kodak Co., or also thermally developed. Thermal development is more preferable, because a processing solution need not be prepared, maintenance of said processing solution is avoided, and comparatively, development time is extremely short.
A thermally developable silver halide photographic light-sensitive material comprising a support having thereon an organic silver salt and a binder is preferably applied to the present invention, from the viewpoint of minimal residual color stain.
When said photosensitive material is processed in a solution, the CPC-2-22 process introduced by Konica Co., or the like, other than the C-41 process previously mentioned, is preferably employed. The development method is not specifically limited, however, preferred is when the photographic light-sensitive material is soaked in a tank of a solution to be processed, alternatively, a processing solution may be sprayed or coated onto the photographic light-sensitive material.
When a silver halide photographic light-sensitive material comprising a dye represented by formulas (1) or (2) is subjected to reversal development, while said silver halide photographic light-sensitive material is being subjected to secondary exposure, an image with excellent resolution can be obtained, and stable photographic characteristics can as well be obtained.
It is advantageous to incorporate a dye represented by the formulas (1) or (2) into a photographic light-sensitive material by applying a solution containing said dye. Incorporation of said dye into said photographic light-sensitive material is preferably carried out by mixing a dye dispersion with gelatin or a binder such as a polymer, and by coating the thus obtained mixture.
When a dye represented by formula (1) is used in the form of a solid dispersion, improvement of resolution is specifically marked and residual color stain is minimal. Specifically, when a photosensitive material is developed in a developing solution, residual color stain is extremely minimal.
It is preferable that the present inventive dye is used in a photographic light-sensitive material for pleasurable photographic viewing, because the residual color stain is minimal.
Use of a filter according to the present invention is not specifically limited, and said filter may be utilized for all usage where the absorption of light is required. Specifically, when said filter is required to absorb infrared rays and it is required that existence of the dye incorporated in a support is not to be noticed with the naked eye, the filter according to the present invention is preferably employed. A support constituting said filter is not specifically limited, and glass, resin and the like can preferably be used.
The dye can be incorporated in the support constituting the filter, or can also be incorporated in a photographic component layer provided on one side of the support, but can also be incorporated in photographic component layers provided on both sides of the support. The photographic component layer(s) provided on either one side or both sides of the support can be obtained through coating, spraying or evaporating a coating solution containing said dye, so that said dye is fixed on either one or both sides of the support. As a method for incorporating the dye into the support, any of the several known methods may be employed. For example, preferable methods may be: (i) said dye is dissolved in a resin and the thus treated resin is casted, or (ii) said dye is dissolved in a resin monomer and the thus treated resin monomer is polymerized. In the case of coating the dye on the support, a binder is preferably used, and as said binder, gelatin, polyvinyl alcohol, polybutyl acrylate or the like may be used.
The absorption amount of infrared rays absorbed by the dye can, if necessary, be adjusted. However, the optical density obtained through absorption by the dye is preferably between 0.01 and 3.0, and is more preferably between 0.1 and 2.0.
Thermally developable photosensitive materials used for forming a photographic image, employing a thermally developing process, are disclosed, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075, and D. Morgan, xe2x80x9cDry Silver Photographic Materialxe2x80x9d and D. Morgan and B. Shely, xe2x80x9cThermally Processed Silver Systemsxe2x80x9d (Imaging Processes and Materials) Neblette, 8th Edition, edited by Sturge, V. Walworth, and A. Shepp, page 2, 1969, etc.
The present invention is preferably applied to a photographic material comprising organic silver salts. Said organic silver salts are reducible silver sources and preferred are organic acid silver salts and silver salts of hetero-organic acids having a reducible silver ion source, specifically, long chain (having from 10 to 30 carbon atoms, but preferably from 15 to 25 carbon atoms) aliphatic carboxylic acid silver salts as well as nitrogen-containing heterocylic ring silver salts.
Organic or inorganic silver salt complexes are also useful in which the ligand has a total stability constant for silver ion of 4.0 to 10.0. Examples of preferred silver salts are described in Research Disclosure, Items 17029 and 29963, and include the following; organic acid salts (for example, salts of gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.); carboxyalkylthiourea salts (for example, 1-(3-carboxypropyl)thiourea, 1-(3-carboxypropyl)-3,3-dimethylthiourea, etc.); silver complexes of polymer reaction products of aldehyde with hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, acetaldehyde, butylaldehyde, etc.), hydroxy-substituted acids (for example, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, silver salts or complexes of thioenes (for example, 3-(2-carboxyethyl)-4-hydroxymethyl-4-(thiazoline-2-thioene and 3-carboxymethyl-4-thiazoline-2-thioene), complexes of silver with nitrogen acid selected from imidazole, pyrazole, urazole, 1,2,4-thiazole, and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benztriazole or salts thereof; silver salts of saccharin, 5-chlorosalicylaldoxime, etc.; and silver salts of mercaptides. Of these, the preferred silver salt is silver behenate. The content of the organic silver salt is 3 g/m2 in terms of silver amount, and is preferably not more than 2 g/m2.
Organic silver salts can be prepared by mixing a water-soluble silver compound with a compound which forms a complex with silver, and employed preferably are a normal precipitation, a reverse precipitation, a double-jet precipitation, a controlled double-jet precipitation as described in JP-A No. 9-127643, etc.
Silver halide grains used in the present invention is specifically not limited, however, in order to minimize the translucence after image formation and to obtain excellent image quality, the average grain size is preferably minute. The average grain size is preferably not more than 0.20 xcexcm; is more preferably between 0.03 and 0.15 xcexcm, and is most preferably between 0.03 and 0.11 xcexcm. The grain size as described herein implies the ridge line length of a silver halide grain when it is a so-called regular crystal which is either cubic or octahedral. When the grain is not a regular crystal, for example, when it is a spherical, cylindrical, or tabular grain, the grain size is the diameter of a sphere having the same volume as each of those grains.
There is no particular limitation on the silver halide grain shape. However, a high ratio occupying a Miller index [100] plane is preferred. This ratio is preferably at least 50 percent; is more preferably at least 70 percent, and is most preferably at least 80 percent. The ratio occupying the Miller index [100] plane can be obtained based on T. Tani, J. Imaging Sci., 29, 165 (1985) in which adsorption dependency of a [111] plane and a [100] plane is utilized.
The composition of silver halide used in the present invention is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, or silver iodide. The photographic emulsion employed in the present invention can be prepared employing methods described in P. Glafkides, xe2x80x9cChimie et Physique Photographiquexe2x80x9d (published by Paul Montel, 1967), G. F. Duffin, xe2x80x9cPhotographic Emulsion Chemistryxe2x80x9d (published by The Focal Press, 1966), V. L. Zelikman et al., xe2x80x9cMaking and Coating Photographic Emulsionxe2x80x9d (published by The Focal Press, 1964), etc. Namely, any of several acid emulsions, neutral emulsions, ammonia emulsions, and the like may be employed. Furthermore, when grains are prepared by allowing soluble silver salts to react with soluble halide salts, a single-jet method, a double-jet method, or combinations thereof may be employed. The resulting silver halide may be incorporated into an image forming layer utilizing any practical method, and at such time, silver halide is placed adjacent to a reducible silver source. Furthermore, silver halide may be prepared by converting a part or all of the silver in an organic silver salt formed through the reaction of an organic silver salt with halogen ions into silver halide. Silver halide may be previously prepared and the resulting silver halide may be added to a solution to prepare the organic silver salt, or combinations thereof may be used, however, the latter is preferred. Generally, the content of silver halide in organic silver salt is preferably between 0.75 and 30 weight percent.
Silver halide employed in the present invention is preferably comprised of ions of metals or complexes thereof, in transition metal belonging to Groups IB, IIB, IIIA, VA, VIA, VIIA and VIII of the Periodic Table. As the above-mentioned metals, preferred are W (in Group VIA); Fe, Co, Ni (in Group VIII); and Cu (in Group IB), Ru, Rh, Pd (in Group VIII), Re (in Group VIIA), Os, Ir, Pt (in Group VIII) and Au (in Group IB).
One type of these metal ions or complex ions may be employed and the same type of metals or the different type of metals may be employed in combinations of two or more types. Generally, the content of these metal ions or complex ions is suitably between 1xc3x9710xe2x88x929 and 1xc3x9710xe2x88x922 mole per mole of silver halide, and is preferably between 1xc3x9710xe2x88x928 and 1xc3x9710xe2x88x924 mole.
Compounds, which provide these metal ions or complex ions, are preferably incorporated into silver halide grains through addition during the silver halide grain formation. These may be added during any preparation stage of the silver halide grains, that is, before or after nuclei formation, growth, physical ripening, and chemical ripening. However, these are preferably added at the stage of nuclei formation, growth, and physical ripening; furthermore, are preferably added at the stage of nuclei formation and growth; and are most preferably added at the stage of nuclei formation. The addition may be carried out several times by dividing the added amount. Uniform content in the interior of a silver halide grain can be carried out. As described in JP-A Nos. 63-29603, 2-306236, 3-167545, 4-76534, 6-110146, 5-273683, etc., incorporation can be carried out so as to result in distribution formation in the interior of a grain. These metal compounds can be dissolved in water or a suitable organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.) and then added. Furthermore, there are methods in which, for example, an aqueous metal compound powder solution or an aqueous solution in which a metal compound is dissolved along with NaCl and KCl is added to a water-soluble silver salt solution during grain formation or to a water-soluble halide solution; when a silver salt solution and a halide solution are simultaneously added, a metal compound is added as a third solution to form silver halide grains, while simultaneously mixing three solutions; during grain formation, an aqueous solution comprising the necessary amount of a metal compound is placed in a reaction vessel; or during silver halide preparation, dissolution is carried out by the addition of other silver halide grains previously doped with metal ions or complex ions. Specifically, the preferred method is one in which an aqueous metal compound powder solution or an aqueous solution in which a metal compound is dissolved along with NaCl and KCl is added to a water-soluble halide solution. When the addition is carried out onto grain surfaces, an aqueous solution comprising the necessary amount of a metal compound can be placed in a reaction vessel immediately after grain formation, or during physical ripening or at the completion thereof or during chemical ripening.
A reducing agent is preferably incorporated into the thermally developable photosensitive material to which the present invention is applied. Examples of suitable reducing agents are described in U.S. Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, and Research Disclosure Items 17029 and 29963, and include the following. Aminohydroxycycloalkenone compounds (for example, 2-hydroxypiperidino-2-cyclohexane); esters of amino reductones as the precursor of reducing agents (for example, piperidinohexose reducton monoacetate); N-hydroxyurea derivatives (for example, N-p-methylphenyl-N-hydroxyurea); hydrazones of aldehydes or ketones (for example, anthracenealdehyde phenylhydrazone; phosphamidophenols; phosphamidoanilines; polyhydroxybenzenes (for example, hydroquinone, t-butylhydroquinone, isopropylhydroquinone, and (2,5-dihydroxy-phenyl)methylsulfone); sulfhydroxamic acids (for example, benzenesulfhydroxamic acid); sulfonamidoanilines (for example, 4-(N-methanesulfonamide)aniline); 2-tetrazolylthiohydroquinones (for example, 2-methyl-5-(1-phenyl-5-tetrazolylthio)hydroquinone); tetrahydroquionoxalines (for example, 1,2,3,4-tetrahydroquinoxaline); amidoxines; azines (for example, combinations of aliphatic carboxylic acid arylhydrazides with ascorbic acid); combinations of polyhydroxybenzenes and hydroxylamines, reductones and/or hydrazine; hydroxamic acids; combinations of azines with sulfonamidophenols; xcex1-cyanophenylacetic acid derivatives; combinations of bis-xcex2-naphthol with 1,3-dihydroxybenzene derivatives; 5-pyrazolones, sulfonamidophenol reducing agents, 2-phenylindane-1,3-dione, etc.; chroman; 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine); bisphenols (for example, bis(2-hydroxy-3-t-butyl-5-methylphenyl)methane, bis(6-hydroxy-m-tri)mesitol, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,5-ethylidene-bis(2-t-butyl-6-methyl)phenol, UV-sensitive ascorbic acid derivatives and 3-pyrazolidones. Of these, particularly preferred reducing agents are hindered phenols.
As hindered phenols, listed are compounds represented by the general formula (A) described below. 
wherein R represents a hydrogen atom or an alkyl group having from 1 to 10 carbon atoms (for example, xe2x80x94C4H9, 2,4,4-trimethylpentyl), and Rxe2x80x2 and Rxe2x80x3 each represents an alkyl group having from 1 to 5 carbon atoms (for example, methyl, ethyl, t-butyl).
Specific examples of the compounds represented by the general formula (A) are described below. However, the present invention is not limited to these examples. 
The used amount of reducing agents first represented by the above-mentioned general formula (A) is preferably between 1xc3x9710xe2x88x922 and 10 moles per mole of silver, and is most preferably between 1xc3x9710xe2x88x922 and 1.5 moles.
Binders suitable for the thermally developable photosensitive material to which the present invention is applied are transparent or translucent, and generally colorless. Binders are natural polymers, synthetic resins, and polymers and copolymers, other film forming media; for example, gelatin, gum arabi, poly(vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetatebutylate, poly(vinyl pyrrolidone), casein, starch, poly(acrylic acid), poly(methylmethacrylic acid), poly(vinyl chloride), poly(methacrylic acid), copoly(styrene-maleic acid anhydride), copoly(styrene-acrylonitrile, copoly(styrene-butadiene, poly(vinyl acetal) series (for example, poly(vinyl formal)and poly(vinyl butyral), poly(ester) series, poly(urethane) series, phenoxy resins, poly(vinylidene chloride), poly(epoxide) series, poly(carbonate) series, poly(vinyl acetate) series, cellulose esters, poly(amide) series. These may be hydrophilic or hydrophobic.
In the present invention, the additional amount of the binder in a photosensitive layer is preferably between 1.5 and 6.0 g/m2, and is more preferably between 1.7 and 5.0 g/m2.
In the present invention, a matting agent is preferably incorporated into the photosensitive layer side. A polymer matting agent or an inorganic matting agent is preferably incorporated in an amount of 0.5 to 10 percent in weight ratio with respect to the total binder in the emulsion layer side.
Materials of the matting agents employed in the present invention may be either organic substances or inorganic substances. Regarding inorganic substances, for example, those can be employed as matting agents, which are silica described in Swiss Patent No. 330,158, etc.; glass powder described in French Patent No. 1,296,995, etc.; and carbonates of alkali earth metals or cadmium, zinc, etc. described in U.K. Patent No. 1.173,181, etc. Regarding organic substances, as organic matting agents those can be employed which are starch described in U.S. Pat. No. 2,322,037, etc.; starch derivatives described in Belgian Patent No. 625,451, U.K. Patent No. 981,198, etc.; polyvinyl alcohols described in Japanese Patent Publication No. 44-3643, etc.; polystyrenes or polymethacrylates described in Swiss Patent No. 330,158, etc.; polyacrylonitriles described in U.S. Pat. No. 3,079,257, etc.; and polycarbonates described in U.S. Pat. No. 3,022,169.
The shape of the matting agent may be crystalline or amorphous. However, a crystalline and spherical shape is preferably employed. The size of a matting agent is expressed in the diameter of a sphere which has the same volume as the matting agent.
The matting agent employed in the present invention preferably has an average particle diameter of 0.5 to 10 xcexcm, and more preferably of 1.0 to 8.0 xcexcm. Furthermore, the variation coefficient of the size distribution is preferably not more than 50 percent, is more preferably not more than 40 percent, and is most preferably not more than 30 percent.
The variation coefficient of the size distribution as described herein is a value represented by the formula described below.
(Standard deviation of grain diameter)/(average grain diameter)xc3x97100
The matting agent according to the present invention can be incorporated into arbitrary construction layers. In order to accomplish the object of the present invention, the matting agent is preferably incorporated into construction layers other than the photosensitive layer, and is more preferably incorporated into the farthest layer from the support surface.
Addition methods of the matting agent according to the present invention include those in which a matting agent is previously dispersed into a coating composition and is then coated, and prior to the completion of drying, a matting agent is sprayed. When a plurality of matting agents are added, both methods may be employed in combination.
A photosensitive material according to the present invention can comprise hydrazine compounds, and preferable hydrazine compounds are described in Research Disclosure, Item 23516 (November 1983 Issue, page 346) and publications cited therein. In addition to the hydrazine compounds described in the above-mentioned publications, listed can be those described in U.S. Pat. Nos. 4,080,207, 4,269,929, 4,276,364, 4,278,748, 4,385,108, 4,459,347, 4,478,928, 4,560,638, 4,686,167, 4,912,016, 4,988,604, 4,994,365, 5,041,355, and 5,104,769; U.K. Patent No. 2,011,391B; European Patent Nos. 217310, 301,799, and 356,898; and Japanese Patent Publication Open to Public Inspection Nos. 60-179734, 61-170733, 61-270744, 62-178246, 62-270948, 63-29751, 63-32538, 63-104047, 63-121838, 63-129337, 63-223744, 63-234244, 63-234245, 63-234246, 63-294552, 63-306438, 64-10233, 1-90439, 1-100530, 1-105941, 1-105943, 1-276128, 1-280747, 1-283548, 1-283549, 1-285940, 2-2541, 2-77057, 2-139538, 2-196234, 2-196235, 2-198440, 2-198441, 2-198442, 2-220042, 2-221953, 2-221954, 2-285342, 2-285343, 2-289843, 2-302750, 2-304550, 3-37642, 3-54549, 3-125134, 3-184039, 3-240036, 3-240037, 3-259240, 3-280038, 3-282536, 4-51143, 4-56842, 4-84134, 2-230233, 4-96053, 4-216544, 5-45761, 5-45762, 5-45763, 5-45764, 5-45765, 6-289524, and 9-160164, etc.
The addional amount of the hydrazine compound is preferably in the range of 10xe2x88x926 to 10xe2x88x921 mole per mole of silver halide and is most preferably in the range of 10xe2x88x925 to 10xe2x88x922 mole.
The hydrazine compound used in the present invention may be dissolved in a suitable organic solvent such as, for example, alcohols (methanol, ethanol, propanol, and fluorinated alcohol), ketones (acetone, methylethyl ketone), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, etc. and then added to the present inventive photosensitive material. Furthermore, according to a well known emulsion dispersion method, the hydrazine compound is dissolved in an oil such as dibutyl phthalate, tricresyl phthalate, glyceryl triacetate or diethyl phthalate, etc., with aid of an auxiliary solvent such as ethyl acetate, cyclohexane, etc., and the thus obtained mixture is mechanically dispersed to result in producing an emulsified dispersion containing said hydrazine compound to be employed for practical use. In addition to the method mentioned above, according to a known method as a solid dispersion method, powders of said hydrazine compound is added to water, and the thus obtained mixture is dispersed using a ball mill, a colloid mill or an ultrasonic homogenizer to result in producing a solid dispersion containing said hydrazine compound to be employed for practical use. In this invention, indazoles (e.g. nitroindazole), which is one of antifoggants, is preferably used in combination with the hydrazine compound.
In this invention, a neucleation accelerating agent such as an amine derivative, an onium salt compound and a hydroxylamine derivative can be used in combination with the hydrazine compound.
The thermally developable photosensitive material, to which the present invention is applied, is stable at normal temperatures and is developed, after exposure, when heated up to high temperatures (for example, from 80xc2x0 C. to 140xc2x0 C.). Upon heating, silver is formed through an oxidation-reduction reaction between the organic silver salt (functioning as an oxidizing agent) and the reducing agent. This oxidation-reduction reaction is accelerated by the catalytic action of a latent image formed in the silver halide through exposure. Silver formed by the reaction with the organic silver salt in an exposed area yields a black image, which contrasts with an unexposed area to form an image. This reaction process proceeds without the further supply of a processing solution such as water, etc. from outside.
The thermally developable photosensitive material, to which the present invention is applied, comprises a support having thereon at least one photosensitive layer, and the photosensitive layer may only be formed on the support. Further, at least one nonphotosensitive layer is preferably formed on the photosensitive layer. The photosensitive layer may be composed of a plurality of layers. Furthermore, for gradation adjustment, in terms of sensitivity, layers may be constituted in such a manner as a fast layer/slow layer or a slow layer/fast layer. Various types of additives may be incorporated into any of a photosensitive layer, a nonphotosensitive layer, or other formed layers. Surface active agents, antioxidants, stabilizers, plasticizers, UV absorbers, covering aids, etc. may be employed in the thermally developable photosensitive material to which the present invention is applied.
Image color control agents are preferably incorporated into the thermally developable photosensitive material to which the present invention is applied. Examples of suitable image color control agents are disclosed in Research Disclosure Item 17029. Preferred image color control agents include phthalazone or phthalazine.
In the photosensitive material to which the present invention is applied, employed can be sensitizing dyes described, for example, in JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242, and 63-15245; U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, and 4,835,096. Useful sensitizing dyes employed in the present invention are described, for example, in publications described in or cited in Research Disclosure Items 17643, Section IV-A (page 23, November 1978), 1831, Section X (page 437, August 1978). Specifically, tricarbocyanines described in JP-A Nos. 59-191032, 60-80841, and dicarbocyanines having a 4-quinoline nucleous represented by the formula (IIIa) and (IIIb) described in JP-A Nos. 59-192242, 3-67242 are advantageously employed. Furthermore, sensitizing dyes described in JP-A Nos. 4-182639, 5-341432, 7-13295, Japanese Patent Examined Publication Nos. 6-52387, 3-10931, U.S. Pat. No. 5,441,866 are preferably used so that the present inventive photographic material can be exposed to infrared laser beam light sources of which wavelength is not less than 750 nm, and additionally not less than 800 nm. These sensitizing dyes may be used singly or in combination of them, and combined usage of these sensitizing dyes are specifically often used for the purpose of super sensitization. Other dyes which do not have spectral sensitizing effect, or compounds which do not substantially absorb visible light, but exhibit super sensitizing effect, can be contained in an emulsion along with the sensitizing dyes.
The dyes used in the present invention can be synthesized according to the method described in U.S. Pat. No. 4,508,811, as well as by the following procedure. According to these methods, derivatives of these dyes can easily be synthesized by a skilled person in this art.
Exemplified synthesizing method will be shown below, but the present invention is not limited thereto.